Increased prefrontal GABA concentrations in adults with autism spectrum disorders.
Adults with autism carry extra GABA in the left planning cortex, flipping the old 'low GABA' story and spotlighting region-specific imbalance.
01Research in Context
What this study did
Maier et al. (2022) scanned adults with autism and matched controls. They used a brain imaging tool called MRS to measure GABA, the brain's main brake signal.
The team focused on the left dorsolateral prefrontal cortex. This spot sits behind the forehead and handles planning and flexible thinking.
What they found
Adults with autism had higher GABA in that left front patch. The boost was clear compared with neurotypical adults.
Levels of glutamate plus glutamine, the gas pedal chemicals, stayed the same in both groups.
How this fits with other research
The result flips two earlier adult studies. Sapey-Triomphe et al. (2019) saw 17% lower GABA in the sensorimotor strip. Harada et al. (2011) also found less frontal GABA in autism. Different brain areas explain the mismatch: motor versus thinking zones.
Child studies look different too. Carvalho Pereira et al. (2018) and Song et al. (2024) found no GABA change in kids with autism. Age seems to matter: kids stay flat, adults rise.
Together the papers map a region-and-age story. GABA dips in motor spots, stays flat in kids, but climbs in adult thinking areas.
Why it matters
You now have solid proof that the brake pedal is up, not down, in the adult planning zone. When you see rigid routines or stuck attention, picture extra inhibition up front. Pair this with the motor-zone brake shortage when you treat sensory defensiveness. Track age: a teen may shift from flat to high GABA, so watch for new rigidity in early adulthood.
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02At a glance
03Original abstract
The excitatory-inhibitory imbalance hypothesis postulates dysregulation of the gamma-aminobutyric acid (GABA) and glutamate (Glu) neurotransmitter systems as a common underlying deficit in individuals with autism spectrum disorders (ASD). Previous studies suggest an important role of these systems in the pathophysiology of ASD, including a study of our group reporting decreased glutamate concentrations in the pregenual anterior cingulate cortex (ACC) of adults with ASD. The aim of this study was to replicate our previous findings of impaired glutamate metabolism in ASD in a new sample and to additionally quantify GABA in the ACC and dorsolateral prefrontal cortex (dlPFC). Concentrations of GABA and glutamate-glutamine (Glx; combined glutamate and glutamine signal) were quantified in the ACC and dlPFC of 43 adults with ASD and 43 neurotypical controls (NTC) by magnetic resonance spectroscopy (MRS). The ASD group showed increased absolute GABA concentrations and elevated GABA/creatine ratios in the left dlPFC compared to NTC, while no group differences were detected in the pregenual and dorsal ACC. Previous findings of altered Glx concentration in the pregenual ACC of the ASD group could not be replicated. Regarding Glx concentrations and Glx/creatine ratios, there were no significant differences in the dlPFC and ACC either. The study supports the hypothesis of an altered GABA and glutamate equilibrium, indicating an imbalance between excitatory and inhibitory metabolism in ASD patients. However, inconsistent results across studies and brain regions suggest a complex underlying phenomenon. LAY SUMMARY: Adults of the autism spectrum exhibit elevated levels of the inhibitory neurotransmitter GABA in the left dorsolateral prefrontal cortex. This finding supports the hypothesis of an imbalance between excitatory and inhibitory equilibrium in patients with autism spectrum disorders.
Autism research : official journal of the International Society for Autism Research, 2022 · doi:10.1002/aur.2740